Channel relay connecting and interlocking system



c. A.' HACKEY CHANNEL RELAY CONNECTING AND INTERLOCKING SYSTEM File'dMarch 29, 1954 mw om.

Patented pr. 7, 1936 rares PATENT OFFICE CHANNEL RELAY ooNNEo'riNG ANDINTERLooniNe SYSTEM Delaware Appiication March 29, 1934, Serial No.I'717,889

9 ..Claims.

The present invention relates. to a system lfor connecting one of agreat number of program studios or sources to a two wire -channel whichmay be in turn connected to a telephone line, transmitter or any otherutilization circuit, and for inhibiting the simultaneous connection ofmore than one studio to said channel.

Broadcasting systems in use today involve a plurality of studios orprogram sources, Vand a plurality of channels or telephone lines runningfrom said sources to transmitters or other utilization circuits. Theprograms sent out from the studios to the channel or channels and fromthence to the transmitters or utilization circuits are synchronized inthat a plurality of programs at the various studios commence at the sametime. By the same time it is meant that they start exactly on the samesecond. Obviously where several studios are to be hooked to one or morechannels which are in turn connected with transmitters or otherutilization circuits there is danger of connecting more than one studioto the same channel.

An object of the present invention is to provide a novel relay systemincluding interlocking connections which prevents more than one studiofrom being connected to the same channel simultaneously. If more thanone studio were connected, to the some transmitter channel, at the sametime the programs would be mixed and this would result in thetransmission of Vunintelligible signals.

An object of the present invention is to include in this novel programdistribution system means for preventing more than one studio to beconnected to a particular channel at the same time due to chattering ofthe contacts for any reason.

In its briefest aspect my invention involves what I have termed achannel relay anda set-up relay for each studio or program source. Thechannel relays and set-up relays may be located in any convenient placeat or remote from the program sources, The system also includes aninterlocking and bridge current relay for all of the channel relays andset-up relays and a bridge circuit having three arms composed of fixedresistances and a fourth arm which is normally disconnected from thebridge circuit. The fourth arm comprises a plurality of resistancesequal in value to the resistances of the other arms. There is aresistance in the fourth arm for each channel relay and when one of saidresistances is connected into the bridge, the bridge is balanced. Adiagonal of the bridge includes a relay which when energized breaks thecircuit between the channel relays, set-up relays, etc. and the sourceenergizing said relays. If any two of said resistances are Iconnected inthe .bridge circuit simultaneously `the bridge circuit is unbalanced,current flows .in the diagonal and the circuit for energizing the relaysbecomes broken and all of the relays return to their normal position.

Normally, that is, when all of the studios are disconnected from thechannel, the bridge circuit is obviously unbalanced. In order to preventthis initial .unbalancing .of the bridge circuit from interrupting therelay energizing circuit, thereby preventing normal operation of therelays when an operator Ycloses a channel relay key I provide a pair ofnormally open contacts -which interrupt the energizing circuit for thebridge, which circuit is connected across the other pair of diagonals ofthe bridge. This last named pair of contacts is closed on .closing aset-up button to complete the bridge energizing circuit immediatelyafter a resistance is included in the fourth arm of the bridge, so that.the bridge rst becomes balanced and then energized as a single studioor program source is connected to the channel, or becomes energized andunbalanced the instant more than one studio or program source isconnected to the channel. In the former case nothing happens, that is,the single studio remains connected to the channel and the program goesout in the desired manner. In the latter case the bridge is unbalanced,current flows through the ydiagonal thereof and the relay energizingsource is disconnected from the relays which all return to their normalpositions.

Many other objects of my invention and advantages owing `from the usethereof will appear from the following detailed description thereof andtherefrom when read in connection with the attached drawing in which thesingle figure illustrates diagrammatically the essential features onlyof my system. Of course I contemplate the inclusion in my system of anynecessary additional apparatus or refinements in general use. Referringto the drawing A, B, C, D and E are studio relay units, eaclr of whichmay be connected as shown by lines to a corresponding studio, therebeing a studio relay unit for each studio or source of programs of thesystem. Studio relays A, B and C are represented by rectangles but therelays in these studios may be the same as the relays shown more indetail in the studio relays D and E. While it will be understood thatthere may be a great number of studios and studio relays, in order tosimplify the description of the apparatus I have shown three studiorelays diagrammatically and two studio relays in details. The studiorelays when actuated operate in accordance with my present invention toconnect the selected studio by way of the studio relays to a telephoneor transmitter line TL.

The relays in each studio relay unit includes a channel relay 5,including a magnetic winding, normally open contacts Il and I8 andnormally closed contact 24. Each studio relay unit includes also aset-up relay comprising a magnet 7 and normally open contacts 25, 26 and23. The entire group of studio relay systems cooperate with a bridgecircuit having three equal resistive arms II, I2 and I3 and a fourth armnormally open-circuited. The fourth arm may be composed of any one of anumber of resistances I4, I5 etc. equal in value to the other arms inthe bridge circuit. Each of the resistances in the fourth arm areadapted under conditions to be described more in detail later to beincluded in the bridge circuit. When the arm is so included in thebridge circuit, the bridge is balanced and even though current isapplied from the high potential source across the bridge there will beno potential difference across the diagonal thereof, and therefore nocurrent will flow in the relay winding Il] connected in the circuitbetween the relay operating battery RB and the energizing circuits ofthe studio relays. My system also includes an interlock and bridgecurrent relay comprising normally closed contacts 29 and normally opencontacts 3G. The normally open contacts 39 are in series with the bridgesource BS connected across the diagonals of the bridge circuit. Mysystem therefore includes a channel relay and set-up relay for eachstudio involved and a balanced bridge current relay for the entire groupof studio relays associated with a single channel.

As pointed out above, the contacts I7 and I8 of the channel relay and23, 25 and 26 of the set-up relay of studio D relays are normally open.Contacts I9 and 29 of the channel relay and 2|, 2'I and 28 of the set-uprelay of studio E relays are normally open. Contacts 24 of the channelrelay of studio D relays and contact 22 of the channel relay of studio Drelays are normally closed. The set-up buttons I and 2 of studio D and Erelays respectively are normally open, while the release keys 3 and 4 ofstudios D and E respectively are normally closed. Contact 29 of theinterlock and bridge current relay is normally closed while contact 39is normally open. The contact 3| of the relay in the diagonal of thebridge circuit is normally closed.

At this point it will be noted that since the relay contacts 23 and 2|of studio D relays and studio E relays respectively, and in any of theother relays in the system are open the bridge circuit includes onlythree arms and therefore is unbalanced. While this is true, however, thecircuit through the winding IG does not become energized because thecontacts 39 are normally open, thereby breaking the circuit through thesource BS connected to the diagonals of the bridge. This prevents thewinding I from being energized and the contacts 3| from being opened tothereby interrupt the circuit between the relay energizing source RB andthe windings in said relays.

It will now be assumed that the operator desires to connect the studio Dto the line TL running to a transmitter or other utilization circuit.This is accomplished by closing the set-up key or button I. This closesa circuit through the winding 'I by way of contacts 24, winding 1,normally closed release key 3 to ground, to the positive terminal ofbattery RB, negative terminal of battery RB, normally closed Contact 3|,normally closed contact 29, and back to set-up button I. Current ows inthe winding of 'I to energize the same and close normally open contacts25 and 26.

Closing normally open contact 26 energizes the winding of relay 5 by wayof 26, lead 40, with the winding of 5, ground, the positive terminal ofbattery RB, the negative terminal of the battery RB, normally closedcontact 3i, lead 4I, closed contacts 25, lead 42 and back to contact 26.

Closing the contacts 25 completes a circuit through the winding of relay9 by way of contacts 25, lead 43, the winding 9, of the interlock relay,ground, the positive terminal of the relay energizing source RB, thenegative terminal of said source, normally closed contacts 3| and lead4I to contacts 25.

Now we have the windings 5 and I of channel and set-up relays andwinding 9 of interlocking bridge current relay energized. These relaysnow act to close normally open contacts I'l, I8 and 23 and open normallyclosed contact 24 at the channel relay of studio D relays and to opennormally closed contact 29 and close normally open contact 30 of theinterlock and bridge curf":

rent relay.

Closing contacts I'I and I8 connects studio D to the outgoing telephoneor transmission line TL. Closing 23 connects one of the resistances,

in this case resistance I5, in the fourth arm of f the bridge circuit byway of contacts 23 and ground. The bridge is now balanced and theclosing of contacts 30 following closing of contacts 25 completes thecircuit between the battery BS and the diagonals of the bridge.

The action of the relay 5 in opening normally closed contact 24interrupts the circuit between the winding of and the source RB at 24.In order to maintain the winding of 'I energized in spite of thisopening of the contacts 24 so that the studio D will remain connected tothe lines TL until disconnected therefrom by an act of the operator, Iprovide a holding circuit by way of contacts 25 which are now closed.This circuit includes the right hand contact of contacts 25, the windingrelease key 3, ground, the positive terminal of source RB, the negativeterminal Of source RB, normally closed contacts 3|, lead 4I, and thecenter contact of contacts 25.

Now We have studio D connected to the outgoing channel TL. Relays 5, 'I'and 9 are energized and the bridge circuit is energized and balanced.The system may at any time be returned to its original state by openingrelease key 3.

If for some reason that is due to chattering or an act of the operatorone of the other studio relay set-up buttons as, for example, set-upbutton No. 2, is closed at the same time that set-up button No. l wasclosed the channel relay winding 8 and set-up relay Winding 8 of studioE will operate in the same manner in which the corresponding relays atstudio D operated, as pointed out hereinbefore in detail, to connectstudio D to line TL and simultaneously connect an additional resistance,say I4, in the fourth arm of the bridge circuit. When the contacts 2| ofthe channel relay in studio E closes to connect resistance |4 in thefourth arm of the bridge, the bridge circuit becomes unbalanced sincethe resistance in the fourth arm is now not equal to `the resistance -inthe remaining arms. `The bridge islunbalanced and an energizing currentflows in the winding of relay lll. This. relay when ,energized opensnormally closed ycontact 3l fwhereby interrupting the circuit betweenthe source -RB and all of the relay windings in the relay systems of thevarious studios. This returns all relays and contacts of the variousstudios` to their normal position so that no studios areconnected to thetransmission line or transmitter line TL.

Only one of a great number of studios as shown, or notshown, may-beconnected to the line TL.

Briey then applicant has provided a novel and simplified means forconnecting any one of a plurality of studios to a transmission line.This meansinoludes a holding circuit which maintains saidstudio soconnected to said transmission line until the operator at the studiorelays actually opens the release key to de-energize the set-up relaywinding. `The system also includes means for preventing more than onestudio frombeing connected ,simultaneously to the transmissionchanneLeither by simultaneous acts of operators, or due to vibration orchattering or other weaknesses in the apparatus. The system includes abalanced bridge circuit and also includes means. for insuring that thebridge circuit is not energized until the relays have had time to insertthe fourth arm of the bridge so that the bridge is balanced whenenergized and therefore does not open the relay energizing circuit.Indicating lights, consisting of small switchboard lamps 1ocatedimmediately above the set-up key and energized in multiple with one ofthe studio relay windings, may indicate to the operator when his channelhas been properly set up.

Having thus describedv my invention and the operation thereof, what Iclaim is:

1. A broadcasting system comprising, a transmission line and a pluralityof program sources, a separate relay for connecting each of said sourcesto said line, and means for returning said relays to normal position`when more than one of said studios are connected simultaneously to saidline including a bridge circuit which is balanced and energized by theoperation of one of said first named relays and unbalanced when morethan one of said relays are actuated to deenergize all of said relays.

2. The combination with a plurality of program sources and atransmission line, of a bridge circuit having three arms, a channelrelay for each of said sources, a plurality of circuits arranged to beconnected in the fourth arm of said bridge when said relays areenergized, there being a circuit for each of said sources, contactsassociated with each of said relays and said sources and line forconnecting a selected one of said sources to said transmission line, andfor connecting one of said circuits in the fourth arm of said bridgetobalance the same, and a relay connected in the diagonal of said bridgeand associated with an additional circuit for energizing said channelrelays to interrupt the same when more than one circuit is connected inthe fourth arm of said bridge to unbalance the same.

3. The combination with a plurality of program sources and atransmission line, of a bridge circuit having three arms, a channelrelay for each of said sources, a circuit for energizing said channelrelays, a circuit for each of said sources including an additionalresistance which is connected in the fourth arm of said bridge tobalance the bridge when the corresponding relay is energized, contactsassociated with each of said channel relays for connecting a selectedone of said studios to said transmission line, and a restoring relayconnected in the diagonal of said bridge and associated with theenergizing circuit for said channel relays to interrupt the same whenmore than one of said channel relays are operated to connect `more thanone of said resistances in the fourth arm of said bridge.

fl. In combination with a plurality of program sources and atransmission line, of means for connecting a selected one of saidsources only to said line comprising, a channel relay for each source,contacts cooperating therewith and with said transmission line and withlines connected to the program source associated therewith, a bridgecircuit, said bridge circuit having three resistive arms, a plurality orresistances, there being a resistance for each of said program sources,a set-up button adapted when closed to energize the winding of saidchannel relay, contacts connected with said channel relay for connectingthe selected one of said program sources to said transmission` line,another set of contacts associated with said set-up relay and adaptedwhen closed to connect the resistance associated with said selectedprogram source in the fourth arm of said bridge whereby said bridge isbalanced, and an additional relay energized by closing said set-upbutton for applying energizing potentials to the diagonals of saidbridge.

5. In combination with a plurality of program sources and a transmissionline, of means for connecting a selected one of said sources only tosaid line comprising, a channel relay for each source, contactscooperating therewith and with said transmission line and with linesconnected to the program source associated therewith, a set-up relay foreach source, a bridge circuit, said bridge circuit having three balancedarms, a plurality of circuits each of an electrical value sufficient tocomprise the fourth arm of said bridge, there being a circuit for eachof said program sources, a set-up button 4adapted when closed toenergize the winding of said set-up relay, contacts connected with saidset-up relay for completing an energizing circuit for said channel relaywhereby said contacts cooperating with said channel relay for connectingthe selected one of said program sources to said transmission line areclosed, another set of contacts associated with said setup relay andadapted when closed to connect one of said plurality of circuitscorresponding with said selected program source in the fourth arm ofsaid bridge whereby said bridge is balanced, and an additional relayenergized by a circut completed by said set-up button for applyingenergizing potentials to the diagonals of said bridge.

6. In combination with a plurality of program sources anda transmissionline, of means for connecting a selected one of said sources only tosaid line comprising a channel relay for each source, contactscooperating therewith and with said transmission line and with linesconnected to the program source associated therewith, a set-up relay foreach source, a bridge circuit, said bridge circuit having three arms, aplurality of resistances, there being a resistance for each of saidprogram sources, a set-up button for each source adapted when closed toenergize the winding of the correspondinor set-up relay, contactsconnected with said set-up relay for completing .a holding Windingtherethrough for energizing said channel relay whereby said contactsconnected with said channel relay are closed to connect the selected oneof said program sources to said transmission line, another set ofcontacts associated with said set-up relay and adapted when closed toconnect the resistance associated with said selected program source inthe fourth arm of said bridge whereby said bridge is balanced, anadditional relay for applying energizing potentials to the diagonals ofsaid bridge, and a relay in the diagonal of said bridge for returningall of said aforesaid relays to normal if more than one of saidresistances are connected in the fourth arm of said bridge.

7. The combination with a plurality of program sources, and atransmission line, of means for connecting a selected one of saidsources to said line comprising, a relay system for each of saidsources, each relay system comprising a channel relay, a set-up relayand a set-up button and a release key, an interlocking-bridge currentrelay for each group of studio relays, a bridge circuit for each groupof studio relays associated with a particular channel, said bridgecircuit comprising three balanced arms, a plurality of resistances eachequal to the resistance in one arm of said bridge there being aresistance for each studio, a circuit including the set-up buttons forenergizing the set-up relay of each studio, contacts associated withsaid set-up relay for closing a holding winding therethrough and forenergizing the corresponding channel relay winding, contacts associatedwith said channel relay winding for completing a circuit connecting theselected one of said program sources to said transmission line, contactsassociated with said set-up relay winding for connecting one of saidresistances in the fourth arm of said bridge, contacts connected withsaid set-up relay winding for completing a circuit through saidinterlock and bridge current relay, contacts associated with saidinterlock and bridge current relay winding for completing a circuitconnecting a source of potential across the diagonals of said bridgecircuit, a. relay connected across the other diagonal of said bridgecircuits, normally closed contacts associated with said relay, saidcontacts normally completing a circuit between an energizing source andsaid channel relays, set-up relays and interlocking bridge currentrelays, whereby when more than one of said set-up buttons are closedsimultaneously more than one of said resistances will be included in thefourth arm of said bridge and said bridge circuit will be unbalanced andenergized and current will flow in said diagonal, thereby interruptingthe circuit between all ol said relays and said energizing sourcethereby returning all of said relays and contacts to their normalposition.

8, A signalling system comprising, a transmission line and a pluralityof signal sources, separate means for connecting any selected one ofsaid sources to said line, and common means for returning saidconnecting means to normal position when more than one of said sourcesare connected simultaneously to said line.

9. In a relay system to be utilized with a broadcasting systemcomprising a transmission line and a plurality of studios, relay meansand circuits to be completed thereby for connecting a selected one ofsaid studios to said line, and relay means for returning said rst .namedrela-y means and said circuits to normal position when more than one ofsaid studios are connected simultaneously to said line.

CHESTER A. RACKEY.

